1. Field of the Invention
This invention relates to electroluminescent metal complexes with dibenzo[f,h]quinoxalines, a process for their preparation, electronic devices comprising the metal complexes and their use in electronic devices, especially organic light emitting diodes (OLEDs). The metal complexes with dibenzo[f,h]quinoxalines show high emission efficiency, excellent vaporizability, thermal stability, processing stability, high charge carrier mobilities, low turn-on voltage and high temperature stability of the emission color.
2. Description of Related Art
JP2005298483 describes an iridium complex, such as, for example,
which can be used for the luminous element and is also suitable for an organic electroluminescent element material, an electrochemiluminescent (ECL) element material, a luminescence sensor, a photosensitizer, a display, etc., its preparation method and a luminous material.
KR20060079625 relates to phosphorescent red-emitting iridium complexes, such as, for example,
and organic electroluminescent device comprising same.
Z. Liu et al, Adv. Funct. Mat. 2006, 16, 1441, describe the use of the complexes
wherein R1 is t-butyl and R2 is
or R1 is t-butyl and R2 is
for highly efficient non-doped organic light emitting diodes.
J.-P. Duan et al., Adv. Mat. 2003, 15, 224, describe the use of the complexes
as orange-red emitters in an OLED.
KR20060036670 relates to phosphorescent iridium complexes and organic electroluminescent devices comprising the same. The following phosphorescent iridium complexes are explicitly disclosed

KR20060079625 relates to iridium complexes represented by the formula
wherein R1, R2, R3, R6, R7 and R8 are independently H, a halogen atom, a carboxy group, an amino group, a cyano group, a nitro group, a C1-C6alkyl group, a C6-C18aryl group, a C1-C6alkoxy group or a C4-C6hetero ring containing a hetero atom such as S or N, or R2 and R3 can be fused to form an aromatic ring; R4 and R5 are independently H, a C1-C6 alkyl group, a C1-C6haloalkyl group, a C6-C18aryl group, a C4-C12hetero ring, an amino group substituted with an alkyl or aryl group, a C1-C6alkoxy group, a cyano group or a nitro group; and X is CH or N (claim 1), and an OLED device containing the metal complex of formula (1).
EP1939208A1 is directed to an organometallic complex having a structure represented by the general formula
    wherein Ar represents an aryl group having 6 to 25 carbon atoms;    A1 represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms;    A2 to A8 each represent any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen group;    M10 represents a metal of Group 9 elements and Group 10 elements;    L10 represents a monoanionic ligand; and    u is 2 when the metal is a Group 9 element, and u is 1 when the metal is a Group 10 element.
WO2009069535 relates to a light-emitting element comprising a light-emitting layer between a first electrode and a second electrode, wherein the light-emitting layer comprises a first organic compound having a hole-transporting property, a second organic compound having an electron-transporting property, and an organometallic complex, wherein a ligand of the organometallic complex has a dibenzo[f,h]quinoxaline skeleton, especially a 2-aryldibenzo[f,h]quinoxaline derivative, and wherein a central metal of the organometallic complex is a Group 9 or Group 10 element.
WO2009157498 relates to metal complexes of the formula
    wherein R1 to R13 represent any of hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms;    M represents a central metal selected from a Group 9 or Group 10 elements;    L10 represents a monoanionic ligand; and u is 2 when the central metal is a Group 9 element or 1 when the central metal is a Group 10 element; and their use in light emitting devices.
WO2009100991 relates to metal complexes of the formula
and their use in OLEDs. Among others compounds of formula
wherein R1 is C2-C10alkyl, R2 is H, or CH3, and L is
are preferred.
WO2005049762 relates to a light-emitting device comprising at least a substrate, an anode, a light-emitting layer and a cathode whereby the light-emitting layer contains an iridium complex IrL3 and whereby at least two ligands L are a dibenzoquinoline. WO2005049762 relates in particular to the complexes Ir(dibenzo[f,h]quinoline)2(pentane-2,4-dionate) and Ir(dibenzo[f,h]quinoline)3 which emit light with a wavelength of λmax=545 nm and λmax=595 nm respectively:

However, there is a continuing need for electroluminescent compounds, especially orange, or red emitters, having improved performance, such as for example, compounds having high emission efficiency, excellent vaporizability, thermal stability, processing stability, high charge carrier mobilities, low turn-on voltage and high temperature stability of the emission color.